Fix cppcheck warnings #28

Job	Run time
build (ubuntu-latest, Release, gcc)	3m 24s
build (ubuntu-latest, Release, clang)	3m 24s
build (ubuntu-latest, Release, mingw-w64-gcc)	4m 11s
build (ubuntu-latest, Debug, gcc)	2m 56s
build (ubuntu-latest, Debug, clang)	2m 48s
build (ubuntu-latest, Debug, mingw-w64-gcc)	4m 18s
build (windows-latest, Release, cl)	5m 3s
build (windows-latest, Debug, cl)	4m 26s
build (macos-latest, Release, gcc)	2m 55s
build (macos-latest, Release, clang)	3m 1s
build (macos-latest, Debug, gcc)	4m 5s
build (macos-latest, Debug, clang)	3m 11s
	43m 42s

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